off 3 base stop at about 8 colossus, get +3 (start armor afterwards), start teching chargelot + archon and tech towards mothership. your goal is to hit a 3 base timing with colossus + archon + mothership BEFORE your opponent has vortex.
Attack when you have enough energy for vortex (maxxed of course, your last supply should be mainly in archons) Vortex the bulk of his army (colossus pref) and you will simply win. If he does not have a vortex and you do, you will win.
Wins all of my PvPs in master league if I get to this point. People just don't tech to mothership quite this fast. The thing is, when you're on 3 base with 8 colossus youre opponent can't really attack into you so you ARE safe to tech up to mothership asap. Vortex is so so so key in this matchup's endgame.
you're welcome ~~~~